<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // var d = new Date();
        // // // d.setDate(d.getDate() + 3);
        // // console.log(d.getDate())
        // function a(){
        //     return 1
        // }
        // // console.log(String(Date.now()).substring(10,13))
        
        // console.log(String.fromCharCode('0x4efe'))

        // console.log('0x4efe')//错误
        // console.log(0x4efe)//错误
        // console.log('\u4efe')//对

    </script>
</body>
</html>